The basic electro-mechanical processes involved in motors and generators are well-known. Mechanical power is produced (in the case of a motor) or electrical energy is generated (in the case of a generator) by the interaction of the electro-magnetic forces between the rotor and stator. While almost all conventional motors utilize electromagnetic forces produced by running current through a series of windings in the form of coils of wire to generate the electro-magnetic field that turns the rotor, the design of motors powered by magnetic fields from permanent magnets date back to as early as the 1840's. For numerous reasons, such permanent magnet powered motors have not been practical or competitive when compared to conventional electrical motors powered by electro-magnetic fields. For general background information on permanent magnets and permanent magnet motor design, reference is made to Moskowitz, Permanent Magnet Design and Application Handbook (1976), Hanselman, Brushless Permanent Magnet Motor Design (2003), and Gieras et al., Permanent Mamet Motor Technology Revised (2003).
Recently a permanent magnet powered motor construct has been proposed that overcomes many of the challenges long associated with permanent magnet motors. U.S. Pat. Nos. 6,246,561 and 6,342,746 issued to Flynn describe methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same. In these patents, a permanent magnet device includes a permanent magnet having north and south pole faces with a first pole piece positioned adjacent one pole face thereof and a second pole piece positioned adjacent the other pole face thereof so as to create at least two potential magnetic flux paths. A first control coil is positioned along one flux path and a second control coil is positioned along the other flux path, each coil being connected to a control circuit for controlling the energization thereof. The control coils may be energized in a variety of ways to achieved desirable motive and static devices, including linear reciprocating devices, linear motion devices, rotary motion devices and power conversion.
It has long been known that certain materials commonly referred to as liquid crystals can be oriented by a magnetic field. As early as 1894, Curie stated that it would be possible for an asymmetric molecular body to polarize in one direction under the influence of a magnetic field. The practical application of this effect is most commonly seen in magnetically ordered crystals even in conditions of symmetry of the molecules of the crystal. U.S. Pat. No. 4,806,858, for example, describes an inspection technique for magnetization that utilizes liquid crystal material to determine whether a sample has been appropriately magnetized. The use of a liquid crystal layer to change the magnetic flux resistance of a single magnetic path was described in Japanese Abstract No. 621 17757A2 (1985).
More recently, the magnetoelectric effects of liquid crystal materials in the form of magnetorestrictive and piezoelectric materials have been the subject of renewed research and development. Generally referred to as magnetoelectric (ME) materials, the research and development into various properties of these ME materials are described, for example, in Ryu et al., “Magnetoelectric Effect in Composites of Magnetorestrictive and Piezoelectric Materials,” Journal of Electroceramics, Vol. 8, 107-119 (2002), Filippov et al., “Magnetoelectric Effects at Piezoresonance in Ferromagentic-Ferroelectric Layered Composites,” Abstract, American Physical Society Meeting (March 2003) and Chang et al., “Magneto-band of the Stacked Nanographite Ribbons,” Abstract, American Physical Society Meeting (March 2003).
While many of the properties of ME materials are understood and there are numerous applications for the use of such liquid crystal materials, there is nothing which suggests how to make effective use of ME materials in the context of the design of permanent magnet motors and the like.